Simviation Forums

Hey,

I just recently got the DreamFleet Dakota (PA-28-236), which comes with a manual, but one of the things the manual doesn't say is what the proper rate of descent is for landing. Speed and all that jazz is in there, but not the rate of descent. I've tried it around 400-500 fpm and generally find myself too high (above the glide slope). I've googled everything I can think of (I'm probably not using the proper terminology, who knows), but can anyone answer this question for me?

Thanks!

You don't fly an approach for a target vertical speed. In fact (especially in light GA), you might as well cover the vertical-speed indicator.

Your goal, is an approach speed (Vref)... then you use pitch to maintain that speed... and then manage your vertical position with the throttle.

Referencing your example: If you started the final approach at the proper altitude; properly configured (gear/flaps/airspeed).. maintaining that airspeed by pitch, and noticed you were a little high (never even glancing at the vertical-speed indicator).. you'd simply reduce power and continue pitching for Vref. If too low.. increase power and continue pitching for Vref.. During this process (especially if there are changing winds).. your vertical speed will fluctuate quite a bit.

Ah, so Vref in the Dakota is 72 KIAS, so if you nail that and start the final approach at the proper altitude, you're good. I suppose that's pretty good information to have 

Thank you for answering and not rolling your eyes, I appreciate it.

[quote]Ah, so Vref in the Dakota is 72 KIAS, so if you nail that and start the final approach at the proper altitude, you're good. I suppose that's pretty good information to have

[quote][quote]Ah, so Vref in the Dakota is 72 KIAS, so if you nail that and start the final approach at the proper altitude, you're good. I suppose that's pretty good information to have

The vertical speed is like an afterthought..

[quote]The vertical speed is like an afterthought..

Your rate of descent on approach is based on the distance between the final approach fix and the decision height, and your ground speed. Say, for example, the distance is six miles and your final approach ground speed is 90 kts. It will take you four minutes to cover that distance. If the descent is from 1500 ft at the final approach fix to a decision height of 200 feet, a descent of 1300 feet, you have to do that in four minutes, making the desired descent rate 325 fpm (1300 divided by four).

Art

Also, keeping in mind that your focus will be on the proper airspeed, which in most cases would make what I am about to say a moot point, but anyway:

It not a very good idea, at least in my experience when descending from a reasonable cruise altitude in a light aircraft, to descend at more than about 800 fpm. Anything more has the potential to be rather uncomfortable to either you or your passengers due to the rapid pressure changes. I say this keeping in mind that there may be a time when you start your descent a little late, and are focused on just getting down rather than nailing a nice speed range for the descent.

Yes, SeanTK is right: airspeed is most important, particularly in not letting it get too slow and risking stalling at a low altitude. Brett is right in that a properly flown approach is accomplished by understanding the relationship between pitch and power.

Mr_Ryan, if you would like to practice airspeed and vertical speed control for a longer period of time than a final approach allows, take your airplane up to, say, 10,000 ft, and set a target approach speed and vertical speed, and try to get both in your descent. Then do it again with different target speeds and rates. I'm sure you will find this very useful in improving your flying.

Have fun!

Art

By all means use those gauges but also pay attention to the plane's attitude as you descend or whatever.

[quote]By all means use those gauges but also pay attention to the plane's attitude as you descend or whatever.